[0az]

I personally use fswatch for this. The invocation is probably something like this:

    fswatch -0 ***.md | xargs -0 make

I invoke a variant of this from my Makefile with a phony watch target. I think the main change is that I also echo a bell character, to provide some feedback.

Fun tip: Preview will automatically reload PDFs on disk, though with some limitations that I workaround by waiting for the bell.